Threaded fastener device with torque control and driver therefore

ABSTRACT

A threaded fastener device is provided with a longitudinally uniform multi-lobular driving cross section characterized by a shearing zone where lobes are sheared off at a substantially predetermined value of applied torque employed for seating the fastener device. The portion of the lobes remaining is capable of sustaining sufficient torque for effecting removal of the seated fastener device. A driver, forming a torque control system with the fastener device, is constructed to engage only the aforementioned shearing zone for severing the lobes within such zone while leaving the aforementioned remaining portion which may be engaged by a second driver for removal of the said fastener device.

iJnited States Patent [191 Reiland THREADED FASTENER DEVICE WITH TORQUECONTROL AND DRIVER THEREFORE [75] Inventor: Bernard F. Reiland,Rockford, Ill.

[73] Assignee: Textron Inc., Rockford, Ill.

[22] Filed: July 14, 1971 [21] Appl. No.: 162,454

[52] US. Cl. 81/121 R, 145/50 A, 85/61 [51] Int. Cl B25b 13/06 [58]Field of Search 145/50 A; 85/61;

[56] References Cited UNITED STATES PATENTS 3,584,667 6/1971 Reiland145/50 A FOREIGN PATENTS OR APPLICATIONS 898,026 6/1962 Great Britain85/61 [451 Oct. 9, 1973 Primary Examiner-Othell M. Simpson AssistantExaminer-James G. Smith v Attorney-Olson, Trexler, Walters & Bushnell [57] ABSTRACT A threaded fastener device is provided with a longitudinallyuniform multi-lobular driving cross section characterized by a shearingzone where lobes are sheared off at a substantially predetermined valueof applied torque employed for seating the fastener device. The portionof the lobes remaining is capable of sustaining sufficient torque foreffecting removal of the seated fastener device. A driver, forming atorque control system with the fastener device, is constructed to engageonly the aforementioned shearing zone for severing the lobes within suchzone while leaving the aforementioned remaining portion which may beengaged by a second driver for removal of the said fastener device.

5 Claims, 7 Drawing Figures PATENTEDUBI 9 m5 SHEET 1 W 2 FIG.

FIG. 3

BERNARD E REILAND INVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMANATTORNEYS PATENTEDUET 9W WEE? 2 BF 2 I I I1 BERNARD F'. [LAND BUCKHORN,BLORE, KLARQUIST &--5PARKMAN ATTORNEYS THREADED FASTENER DEVICE WITHTORQUE CONTROL AND DRIVER THEREFORE BACKGROUND OF THE INVENTION Threadedfastener devices are frequently seated with a power operated or manuallyoperated torque wrench, when predetermined tension on the fastenerdevice is required for securing members joined thereby. Torque wrenchesare subject to human error in operation, and moreover, it is difficultto ascertain from a fastener device driven by a torque wrench whether ornot the same has been seated properly.

One solution of this problem has been to provide fastener devices whichthemselves transmit only a predetermined driving torque, and which thenprovide some indication of having been thus driven. Some devices of thistype are difficult to manufacture. For instance, a fastener device maybe formed having a pair of driving heads separated by a narrow neck orgroove at which point shearing will take place as predetermined torqueis applied to an outer driving head. The remaining driving head may thenbe employed for effecting subsequent removal of the fastener device.Manufacture of a unit providing such neck or groove would ordinarilyrequire a separate machining operation for the groove.

SUMMARY OF THE INVENTION According to the present invention, a fastenerdevice is provided which has a substantially unitary driving head ordriving configuration of substantially uniform longitudinal crosssection comprising a series of radi' ally outwardly extending protrudentmeans or lobes. The driving configuration includes a shearing zone orportion adapted to be engaged by a driver which shears off theprotrudent means or lobes within such shearing zone when a substantiallypredetermined value of seating torque is applied to the driver forseating said fastener device. However, the driver leaves said protrudentmeans or lobes intact within a second zone or portion of said drivingconfiguration wherein the latter is adapted to be engaged by a seconddriver for effecting removal of the fastener device. The longitudinalextent of the second zone or portion is desirably at least as great asthe longitudinal extent of the shearing zone whereby adequate drivingengagement for removal of said fastener device is assured.

According to a particular aspect of the present invention in a preferredembodiment thereof, a driver cooperable with a driving configuration ofthe fastener device is arranged to engage preferentially theaforementioned shearing zone while avoiding the zone reserved foreffecting removal. The fastener device and such driver comprise aneffective controlled torque transmitting system according to the presentinvention. A second driver may subsequently be employed for removing thefastener device as necessary.

It is an object of the present invention to provide an improved fastenerdevice for selectively transmitting a predetermined value of appliedtorque and for indicating when such a value of torque has been appliedfor seating the fastener device.

It is another object of the present invention to provide an improvedcontrolled torque fastener device having a driving configuration oflongitudinally uniform cross section whereby manufacture thereof issimplified.

It is a further object of the present invention to provide an improvedcontrolled torque fastener device of longitudinally uniform crosssection provided with a shearing zone adapted to be engaged for shearinga portion of the driving configuration of said fastener device whileleaving an easily engageable driving region capable of effecting removalof said fastener device.

It is another object of the present invention to provide an improveddriver for engaging the driving configuration of a fastener device forcausing said fastener device to transmit predetermined torque.

It is a further object of the present invention to provide an improvedtorque-transmitting system for placing a fastener device underpredetermined tension.

The subject matter which I regard as my invention is particularlypointed out and distinctly claimed in the concluding portion of thisspecification. The invention, however, both as to organization andmethod of operation, together with further advantages and objectsthereof, may best be understood by reference to the followingdescription taken in connection with the accompanying drawings whereinlike reference characters refer to like elements.

DRAWINGS FIG. 1 is a partially broken away elevation of atorque-transmitting system according to the present invention includinga fastener device according to the present invention and a drivertherefor;

FIG. 2 is a more detailed elevational view of the threaded fastenerdevice according to the present invention, engaged by a driver, shown incross section and partially shown in phantom, by means of which apredetermined value of torque can be transmitted;

FIG. 3 is a partially broken away cross-sectional view of the driveralso illustrated in FIGS. 1 and 2;

FIG. 4 is a transverse cross section of a threaded fastener deviceaccording to the present invention and driver therefor, as taken at 4-4in FIG. 2;

FIG. 5 is an elevational view of a threaded fastener device according tothe present invention after the same has been seated with apredetermined value of torque for removing a portion of said fastenerdevice, together with a second driver for said fastener device employedfor effecting removal of same, the second driver being illustrated incross section;

FIG. 6 is a top view of the FIG. 5 fastener device having had a portionthereof removed by the application of predetermined torque; and

FIG. 7 is an elevational view of a second form of fastener deviceengaged by a third form of driver, illustrated in cross section, adaptedto seat such fastener device with a predetermined value of torque.

DETAILED DESCRIPTION Referring to FIGS. 1, 2, and 4 a fastener deviceaccording to the present invention is illustrated having a threadedshank l0 and a driving head 12 characterized by a driving formationincluding a plurality of out wardly extending longitudinal protrudentmeans or lobes l4 separated by inwardly recessed flutes. In thepreferred embodiment, there are six such lobes. The lower portion of thehead is also provided with an enlarged base or hearing washer portion16. The lobes are reinforced next to the bearing washer by means ofshoulders 18 which slope inwardly from the lower extremity of the lobesand upwardly toward the inwardly recessed longitudinal flutes. 1

A fastener device having this general head configuration is describedand claimed in my US. Pat. No. 3,584,667, granted June l5, 1971,entitled Coupling Arrangement and Tools for Same, that patent being acontinuation-in-part of application Ser. No. 624,853 filed Mar. 21,1967, and which in turn was a continuation-in-part of my applicationSer. No. 580,223, filed Sept. 19, 1966. The centers or axes of curvatureof the lobes 14 are suitably located at the apices of a regular hexagon,while the recessed flutes, having a larger radius of curvature than thelobes, merge smoothly and tangentially therewith. This driving headpermits a matching driving tool to supply a positive and predetermineddriving torque without slipping of the tool or rounding off ofprojections.

ln FIGS. 1 and 2, the fastener device is illustrated as threadablyengaged with a matingly threaded workpiece 19 to which an aperturedstructural member 21 is secured by means of the head of the fastenerdevice, and specifically bearing washer portion 16 thereof.Alternatively, the fastener device may be of the self tapping variety.It is desired that the shank of the fastener device be placed underpredetermined tension for adequately securing member 21 in place.Driving torque will be employed as a gauge of such tension, with therelationship therebetween being experimentally ascertainable for aparticular environment as influenced by frictional factors.

The fastener device according to the present invention is provided witha driving head having the above described multi-lobular driving crosssection which is substantially uniform in a longitudinal direction, butwhich includes first and second portions, with the first portiondefining a shearing zone wherein the portions of lobes 14 within suchzones are dimensioned to shear off at a substantially predeterminedvalue of seating torque for the fastener device or value within apredetermined torque range. This first portion, or shearing zone, isdesignated by the letter A in FIG. 2, and extends downwardly from thetop of the driving head for a distance less than half of the height ofthe head above bearing washer 16. The driving head 12', having the lobessheared off in the aforementioned shearing zone, is further illustratedin FIG. 5.

The driving heads second zone, designated by the letter K in FIG. 2, isdimensioned for sustaining sufficient driving torque for subsequentlyeffecting removal of the fastener device from the workpiece or matinglythreaded means engaged by the fastener device. Thus, assuming thefastener device is driven into a threaded member with sufficient torquefor bringing about shearing in shearing zone A as hereinafter more fullydescribed, the remaining portion, K, should desirably sustain an equalvalue of torque which may be required for removing the fastener devicefrom the mating threaded member. While the removal torque is frequentlyless than the seating torque required for placing the fastener deviceunder tension, it is nonetheless preferred that the dimension, K, exceedthe dimension A. The sum of A and K equals the dimension K, or the fulllobe height of the driving head. It will be appreciated, of course, thatsome driving contact may also be procured below such full lobeconfiguration of the driving head for reinforcing the adaptability ofthe fastener device for removal from a workpiece after being torqued toa tension condition. Removal ability is thus assured.

The driver for the fastener device as thus far described is providedwith an internal surface configuration including longitudinal recessesfor mating with the driving head lobes. The driver is generallycomplementary in cross section to the driving head except the surfacesare so dimensioned that there will be a reasonable amount of clearanceto permit ready assembly of the driver over the fastener device head. Adriver 20 for applying seating torque to the fastener device accordingto the present invention and thereby placing the same under apredetermined amount of tension is illustrated in FIGS. 1, 2, and 3. Thedriving head and the driver therefor form a torque transmitting systemfor providing the proper amount of torque for seating a given fastenerdevice.

In FIG. 1, the driver, 20, is shown assembled over the head 12 of thefastener device. The driver comprises a coupling portion 22 providedwith a circumferential inner surface 25 which is complementary to theperipheral configuration of head 12 as previously described. However,this configuration is complementary only with the upper portion A of thedriving head, as defined in connection with FIG. 2, with the remainderof the driver comprising a hollow cylindrical socket 26, the interior ofwhich is spaced outwardly from the lobes of the driving head. The lowerend of the socket is adapted for resting upon washer 16, thereby spacingthe complementary portion 25 of the driver thereabove so it will onlyengage portion A of the driving head. Since the lower end of the socketis designed to rest upon washer 16, the inside diameter of the socket atthis point will naturally be less than the outside diameter of washer16. The lower inner corner of the driver is provided with a slight bevelor chamfer to match the upper bevel of the washer.

The driver or tool 20 also includes an upper coupling portion 28 whichis provided with a recess for cooperatively receiving end 30 of a shaftforming a part of a power unit 32. The recess and the end 30 aresuitably of square cross section, and the square end 30 is adapted to besnapped in place through engagement with a detent ball 34.

Referring to FIG. 3, showing the driver in greater detail andparticularly inner surface 25 thereof, the longitudinal recesses 36 maybe seen which are adapted to receive lobes 14 of the fastener devicehead. Between these longitudinal recesses are located inwardly extendingconvexly rounded surfaces which mate with the inter-lobe flutes of thefastener device head. The side of one of such surfaces is illustrated at38 in FIG. 3, and also partially in phantom in FIG. 2. This surfaceengages the opposing side of lobe 14' only within the shearing zone Athereof, whereby when the proper torque is applied, the portion of lobe14 within such shearing zone will shear off. The inner configuration 25is chamfered at 40 to provide an upper chamfer upon the driving surfaceof the head remaining after the lobe in zone A has been removed.

When driver 20 is rotated in a clockwise direction, the fastener devicewill be threaded into a mating tapped thread in workpiece 19 until thefastener device is drawn up tight with washer 16 bearing against member21. Further torque is then applied up to the value of a substantiallypredetermined seating torque desired. At this point, the lobes 14 aresevered in the aforementioned shearing zone. Turning to FIG. 5,illustrating the fastener device having the lobes thereof sheared offwithin the aforementioned zone A, it can be seen the remainder of thelobes, 14K, have been chamfered at 42. The appearance of the drivinghead is, however, sufficiently different from its former appearance asillustrated in FIGS. 1 and 2 that a ready indication is given ofpredetermined applied torque. Thus, properly seated fastener devices canbe ascertained by visual inspection.

As hereinbefore mentioned, the inner surfaces of the driver were sodimensioned that a reasonable amount of clearance occurs between driverand the fastener device head whereby a driver may be easily applied andremoved. Consequently, the driving head in zone A is not stripped to acompletely cylindrical configuration, but rather a residual root portionof the lobes remains at 44 defining the shearing surface. The shearingcross section, represented by the sum of an area 44 and an area 42,multiplied by six represents the total root cross section which must besheared by driver 20. This total area, equal to about half thecircumferential area in shearing zone A after the lobes are removed, isdesigned to shear at substantially the desired value of seating torque.Such total area should be less than the cross-sectional area of shank atthe minor diameter of the thread thereof whereby lobe shearing will takeplace before the head 12' shears from the shank of the fastener device.The corresponding cross section of the lobe portions remaining, i. e.,the root cross section of a lobe 14K, multiplied by six for the numberof lobes, should exceed the cross-sectional area of the shank at theminor thread diameter to prevent failure of the driving head in removingthe fastener device.

For removing the fastener device from a workpiece after the same hasbeen driven with sufficient torque to remove the lobes in theaforementioned shearing zone, a second tool or driver 46 is employedhaving an interior configuration 48 for complementarily engaging lobes14K. i. e., the interior of the socket is provided with longitudinalrecesses 49 for receiving lobes 14K. The mating lobular configuration ofthe driver may be present for substantially the whole depth of thesocket of driver 46, but of course, since only the height of lobes 14Kneed be engaged, such interior configuration need extend only for theheight of such lobes. The lower end of the socket, as viewed in FIG. 5,is suitably beveled to match the bevel on the upper edge of bearingwasher 16 and sloping shoulders are suitably provided interior thedriver for mating with shoulders 18 of the driving head. Thus, as thedriver 46 is turned in a counterclockwise direction, a sufficient torquemay be applied for removing the fastener device from workpiece 19.

Although the driver 20 illustrated in FIG. 1 is preferred, wherein themeans for preventing simultaneous engagement of the driver with theportion K of the thread constitutes an open-end socket, other drivingmeans are applicable for shearing the lobes in shearing zone A. One suchalternative form of driver is illustrated in FIG. 7, and is hereillustrated as applied to a fastener device according to the presentinvention which in this instance is shown as comprising a nut 52 havingan internally threaded bore indicated at 50. The nut 52 may be otherwisesubstantially similar to the driving head 12 as hereinbefore described.

The driver, illustrated at 53 as partially broken away, has an internalconfiguration substantially mating with the external configuration ofnut 52, which is also of the type illustrated in FIG. 4. However, thetool is foreshortened such that the driving head engages the nut onlyfor the length of shearing zone A, without engaging the major portion oflobes 54. The end wall 56 of the socket of driver 54 is arranged to abutthe top surface 58 of the nut 52 whereby the configuration of the driverengages only the top portion of the nut as indicated. Consequently, whenpredetermined torque is applied, the lobes in shearing zone A will besevered, leaving lobes in a removal zone. Also, it is readily determinedupon visual inspection that the nut has been thus seated. The lowerportion of the internal configuration of the drivers convex surfaces arechamfered at 60 to produce a similar chamfer upon the portion of thelobes 54 remaining. The remaining portion of lobes 54, desirably havinga full lobe height greater than the portion of the lobes severed, isreadily engageable with a separate tool, such as illustrated at 46 inFIG. 5, for removal of the nut. Since the portion of the lobes remainingis greater than the portion severed, the ability to transmit removaltorque is assured.

While I have shown and described preferred embodiments of my invention,it will be apparent to those skilled in the art that many changes andmodifications may be made without departing from my invention in itsbroader aspects. I therefore intend the appended claims to cover allsuch changes and modifications as fall within the true spirit and scopeof my invention.

I claim:

1. A torque transmitting system comprising a driving member and a driventhreaded fastener device member, said driven member being provided withradially directed protrudent means adapted to receive said drivingmember, said radially directed protrudent means having a first portionadapted to be engaged by said driving member and a second portioncomprising a substantial continuation of the first portion, said drivingmember including means permitting said driving member to engage only thefirst portion of said radially directed protrudent means, whilepreventing simultaneous engagement with the second portion of saidprotrudent means, said first portion of said radially directedprotrudent means being dimensioned to transmit torque up to asubstantially predetermined value from said driving member to saiddriven member at which value shearing of said first portion of saidprotrudent means takes place as said fastener device is tightenedrelative to a mating threaded member to place said driven member inpredetermined tension relative to said mating member, said secondportion of the same protrudent means being dimensioned to transmit saidvalue of torque adapting the same for subsequent engagement for removingsaid driven member from a mating member.

2. A torque transmitting system comprising: a fastener device adapted toengage a second member in threadably mating relation, said fastenerdevice having a driven head provided with an outer configurationincluding a plurality of outwardly extending, radially directedlongitudinal lobes separated by inwardly recessed longitudinal flutes,the said configuration having a length including a first longitudinalportion and a second longitudinal portion being a continuation of saidfirst portion and of longer effective length than the first adapting thelobes in the said first portion to shear off at a substantiallypredetermined value of torque applied to said driven head, and a drivingmember provided with an inner configuration including longitudinalrecesses for mating with said radially directed lobes, said driven headhaving an abutment surface against which said driving member ispositionable with said inner and outer configurations in matingrelation, said abutment surface locating said driving memberlongitudinally relative to the driven head with said inner configurationof said driving member in driving relation with said driven head onlyfor the length of the said first portion thereof for shearing off thelobes thereof as said driving member applies said predetermined value oftorque when said fastener device is initially driven into matingrelation with the threadably mating member, said second portion of theouter configuration of the driven head having an effective lengthadapting the same to transmit at least said predetermined value oftorque for removing said fastener device from said threadably matingmember.

3. The system according to claim 2 wherein said abutment is provided bya washer flange located on said driven head adjacent said second portionof said outer configuration thereof, said driving member comprising asocket having said inner configuration on the interior of said socket inlongitudinally spaced relation with the outer open end of said socketfor engaging said first portion of said head, the open end of saidsocket having an inside diameter less than the outside diameter of saidwasher flange and greater than the outside diameter of said outerconfiguration of said head for the longitudinal distance between theouter open end of said socket and the said inner configuration of saiddriving member.

4. A torque transmitting system according to claim 1, wherein saiddriving member comprises a socket having an internal wall configurationincluding at least one segment thereof adapted for engagement with saidfirst portion of said radially directed protrudent means on the drivenmember, and said means for preventing simultaneous engagement comprisinga cylindrical extension on said socket said extension having an innersurface spaced from said radially directed protrudent means of saidsecond portion thereof, and flange means formed on said driven threadedfastener for engagement by said cylindrical extension to limit therebyengagement of said driven member with said protrudent means to only saidfirst portion thereof.

5. A torque transmitting system as defined in claim 1, wherein saiddriven member comprises a socket having an inner wall surface configuredto engage said first portion of said radially directed protrudent means,and said means for preventing simultaneous engagement with said secondportion of said radially directed protrudent means comprising an endwall formed in said socket for engagement with the top surface of saiddriven member whereby engagement of said socket and said radiallydirected protrudent means is limited only to said first portion thereof.

1. A torque transmitting system comprising a driving member and a driventhreaded fastener device member, said driven member being provided withradially directed protrudent means adapted to receive said drivingmember, said radially directed protrudent means having a first portionadapted to be engaged by said driving member and a second portioncomprising a substantial continuation of the first portion, said drivingmember including means permitting said driving member to engage only thefirst portion of said radially directed protrudent means, whilepreventing simultaneous engagement with the second portion of saidprotrudent means, said first portion of said radially directedprotrudent means being dimensioned to transmit torque up to asubstantially predetermined value from said driving member to saiddriven member at which value shearing of said first portion of saidprotrudent means takes place as said fastener device is tightenedrelative to a mating threaded member to place said driven member inpredetermined tension relative to said mating member, said secondportion of the same protrudent means being dimensioned to transmit saidvalue of torque adapting the same for subsequent engagement for removingsaid driven member from a mating member.
 2. A torque transmitting systemcomprising: a fastener device adapted to engage a second member inthreadably mating relation, said fastener device having a driven headprovided with an outer configuration including a plurality of outwardlyextending, radially directed longitudinal lobes separated by inwardlyrecessed longitudinal flutes, the said configuration having a lengthincluding a first longitudinal portion and a second longitudinal portionbeing a continuation of said first portion and of longer effectivelength than the first adapting the lobes in the said first portion toshear off at a substantially predetermined value of torque applied tosaid driven head, and a driving member provided with an innerconfiguration including longitudinal recesses for mating with saidradially directed lobes, said driven head having an abutment surfaceagainst which said driving member is positionable with said inner andouter configurations in mating relation, said abutment surface locatingsaid driving member longitudinally relative to the driven head with saidinner configuration of said driving member in driving relation with saiddriven head only for the length of the said first portion thereof forshearing off the lobes thereof as said driving member applies saidpredetermined value of torque when said fastener device is initiallydriven into mating relation with the threadably mating member, saidsecond portion of the outer configuration of the driven head having aneffective length adapting the same to transmit at least saidpredetermined value of torque for removing said fastener device fromsaid threadably mating member.
 3. The system according to claim 2wherein said abutment is provided by a washer flange located on saiddriven head adjacent said second portion of said outer configurationthereof, said driving member comprising a socket having said innerconfiguration on the interior of said socket in longitudinally spacedrelation with the outer open end of said socket for engaging said firstportion of said head, the open end of said socket having an insidediameter less than the outside diameter of said washer flange andgreater than the outside diameter of said outer configuration of saidhead for the longitudinal distance between the outer open end of saidsocket and the said inner configuration of said driving member.
 4. Atorque transmitting system according to claim 1, wherein said drivingmember comprises a socket having an internal wall configurationincluding at least one segment thereof adapted for engagement with saidfirst portion of said radially directed protrudent means on the drivenmember, and said means for preventing simultaneous engagement comprisinga cylindrical extension on said socket said extension having an innersurface spaced from said radially directed protrudent means of saidsecond portion thereof, and flange means formed on said driven threadedfastener for engagement by said cylindrical extension to limit therebyengagement of said driven member with said protrudent means to only saidfirst portion thereof.
 5. A torque transmitting system as defined inclaim 1, wherein said driven member comprises a socket having an innerwall surface configured to engage said first portion of said radiallydirected protrudent means, and said means for preventing simultaneousengagement with said second portion of said radially directed protrudentmeans comprising an end wall formed in said socket for engagement withthe top surface of said driven member whereby engagement of said socketand said radially directed protrudent means is limited only to saidfirst portion thereof.